/*-----------------------------------------
   HELLOBIT.C -- Bitmap Demonstration
                 (c) Charles Petzold, 1998
  -----------------------------------------*/

#include <windows.h>
#include "resource.h"

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
	PSTR szCmdLine, int iCmdShow)
{
	static TCHAR szAppName [] = TEXT ("HelloBit") ;
	HWND         hwnd ;
	MSG          msg ;
	WNDCLASS     wndclass ;

	wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
	wndclass.lpfnWndProc   = WndProc ;
	wndclass.cbClsExtra    = 0 ;
	wndclass.cbWndExtra    = 0 ;
	wndclass.hInstance     = hInstance ;
	wndclass.hIcon         = LoadIcon (NULL, IDI_APPLICATION) ;
	wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
	wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
	wndclass.lpszMenuName  = szAppName ;
	wndclass.lpszClassName = szAppName ;

	if (!RegisterClass (&wndclass))
	{
		MessageBox (NULL, TEXT ("This program requires Windows NT!"),
			szAppName, MB_ICONERROR) ;
		return 0 ;
	}

	hwnd = CreateWindow (szAppName, TEXT ("HelloBit"), 
		WS_OVERLAPPEDWINDOW, 
		CW_USEDEFAULT, CW_USEDEFAULT,
		CW_USEDEFAULT, CW_USEDEFAULT,
		NULL, NULL, hInstance, NULL) ;

	ShowWindow (hwnd, iCmdShow) ;
	UpdateWindow (hwnd) ;

	while (GetMessage (&msg, NULL, 0, 0))
	{
		TranslateMessage (&msg) ;
		DispatchMessage (&msg) ;
	}
	return msg.wParam ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	static HBITMAP hBitmap ;
	static HDC     hdcMem ;
	static int     cxBitmap, cyBitmap, cxClient, cyClient, iSize = IDM_BIG ;
	static TCHAR * szText = TEXT (" Hello, world! ") ;
	HDC            hdc ;
	HMENU          hMenu ;
	int            x, y ;
	PAINTSTRUCT    ps ;
	SIZE           size ;

	switch (message)
	{{
	case WM_CREATE:
		hdc = GetDC (hwnd) ;
		hdcMem  = CreateCompatibleDC (hdc) ;

		GetTextExtentPoint32 (hdc, szText, lstrlen (szText), &size) ;
		cxBitmap = size.cx ;
		cyBitmap = size.cy ;
		hBitmap = CreateCompatibleBitmap (hdc, cxBitmap, cyBitmap) ;

		ReleaseDC (hwnd, hdc) ;

		SelectObject (hdcMem, hBitmap) ;
		TextOut (hdcMem, 0, 0, szText, lstrlen (szText)) ;
		return 0 ;

	case WM_SIZE:
		cxClient = LOWORD (lParam) ;
		cyClient = HIWORD (lParam) ;
		return 0 ;

	case WM_COMMAND:
	{
		hMenu = GetMenu (hwnd) ;
		int cmdid = LOWORD (wParam);

		switch (cmdid)
		{
		case IDM_BIG:
		case IDM_SMALL:
			
			// static `iSize` is the previous CMDID
			CheckMenuItem (hMenu, iSize, MF_UNCHECKED) ;
			
			iSize = cmdid;
			CheckMenuItem (hMenu, iSize, MF_CHECKED) ;
			InvalidateRect (hwnd, NULL, TRUE) ;
			break ;
		}
		return 0 ;
	}

	case WM_PAINT:
		hdc = BeginPaint (hwnd, &ps) ;

		switch (iSize)
		{
		case IDM_BIG:
			StretchBlt (hdc, 0, 0, cxClient, cyClient, 
				hdcMem, 0, 0, cxBitmap, cyBitmap, SRCCOPY) ;
			break ;

		case IDM_SMALL:
			for (y = 0 ; y < cyClient ; y += cyBitmap)
				for (x = 0 ; x < cxClient ; x += cxBitmap)
				{
					BitBlt (hdc, x, y, cxBitmap, cyBitmap, 
						hdcMem, 0, 0, SRCCOPY) ;
				}
				break ;
		}

		EndPaint (hwnd, &ps) ;
		return 0 ;

	case WM_DESTROY:
		DeleteDC (hdcMem) ;
		DeleteObject (hBitmap) ;
		PostQuitMessage (0) ;
		return 0 ;
	}}

	return DefWindowProc (hwnd, message, wParam, lParam) ;
}
